Biologists with the Florida Fish and Wildlife Conservation Commission's Fish and Wildlife Research Institute documented 337 manatee carcasses in state waters in 2008. The report said 90 of the deaths were watercraft-related and a record 101 deaths were newborns.

The report said a variety of factors could have contributed to the high number of newborn deaths, including the possibility there were more manatee births or that biologists recovered a higher proportion of manatee calf carcasses.

Researchers said a reduction in the number of red tide-related deaths helped keep the overall manatee mortality rate last year below the five-year average of 357.